In the fields of photometry and optical spectroscopy to determine the concentration of a gas component in a test gas by means of absorption measurement, the problem arises with the measuring sample cell that the transmission of the empty sample cell without any target gas present, and therefore without any absorption due to the target gas, must be known in order to be able to identify the target gas by evaluating the gas-dependent absorption.
A known solution consists in flushing the sample cell with a gas from a reservoir, for example a compressed gas bottle, which does not contain the gas components to be measured and also does not absorb in the wavelength region being used. Nitrogen, for example, is usable for this purpose if ambient air is used as the test gas. Since conventional measuring cells usually have large volumes, depending on their application, being typically >100 cm3 to several liters, and a flushing gas volume which is a multiple of the measuring cell volume is needed for each flushing operation, then for continuously running or large numbers of measuring processes, this results in a substantial consumption of gas.